EXPRESSION OF RENIN AND ITS MESSENGER-RNA IN THE ADULT-RAT KIDNEY WITH CHRONIC URETERAL OBSTRUCTION

Angiotensin II has been implicated in mediating renal vasoconstriction resulting from chronic unilateral ureteral obstruction (UUO) in both mature and developing animals. We have previously shown that chronic neonatal UUO results in increased distribution of renin and its mRNA in the obstructed kidney, as well as of immunoreactive renin in the intact opposite kidney. The present study was designed to evaluate the effects of 24 hours versus 4 weeks of UUO on the distribution of renin mRNA and its protein in the adult rat kidney. Renin was detected by immunocytochemistry using a polyclonal anti-rat renin antibody. Renin mRNA was localized by in situ hybridization to an oligonucleotide complementary to renin mRNA. UUO of 24 hours' or 4 weeks' duration did not alter the distribution of renin and its mRNA in the obstructed kidneys as compared with sham-operated kidneys, although kidneys obstructed for 4 weeks had a significant increase in the percent of renin-containing juxtaglomerular apparatuses (JCA) when compared with the intact opposite kidneys (P < 0.05). Compensatory hypertrophy was not present in the intact opposite kidneys after 24 hours of UUO and distribution of renin gene expression was not altered at that time. However, 4 weeks following contralateral UUO, the intact kidneys were hypertrophied and showed a decrease in renin gene expression relative to the obstructed and sham-operated kidneys. We conclude that unlike UUO during early development, chronic UUO in the mature animal does not activate renin gene expression nor alter renin distribution in the obstructed kidneys. Renin gene expression is suppressed in the hypertrophied kidney with prolonged contralateral UUO. The response of intrarenal renin to chronic UUO appears to be agedependent, with the mature animal having an attenuated response compared with that of the developing animal. © 1990, National Kidney Foundation, Inc.. All rights reserved.